Digital Loopback Testing (At&T3) - 3Com 56K Command Reference Manual

Digital Loopback
Testing (AT&T3)
1 Send the command
2 Establish a connection with the remote device.
3 Send the Business Modem the escape code,
4 Send
5 Have the remote user type a short message. It will be looped back by your
6 When the remote user has completed the test, send the escape code,
7 Send
This test can help you locate a problem with a remote device or with the
telephone line. The figure below shows the data flow during Digital
Loopback (DL) testing.

 

 

  


AT&M0&N3S14.0=0
testing.
This command disables error control, fixes the connection rate at 2400
bps, and makes the Business Modem return to command mode when
you type +++.
Command mode.
to the modem to enter Digital Loopback mode.
AT&T3
Business Modem's transmitter for verification on the remote user's
screen. You will not see the message or any other data.
, and then to end the test.
+++ AT&T0
Alternatively, you can end the test by sending ATH or ATZ. Be careful,
because ATZ resets the modem in addition to ending the test.
In any case, the Business Modem responds OK. If the modem sends an
ERROR message, you have issued an invalid command.
, unless you used ATZ.
AT&M4
Testing the Business Modem using AT&Tn




to the modem to prepare for
+++
14-5

 

 

  
 
, to bring it back to